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[Esch]

http://www.bbc.co.uk/news/science-environment-24429621

Researchers at a US lab have passed a crucial milestone on the way to their ultimate goal of achieving self-sustaining nuclear fusion.

Harnessing fusion - the process that powers the Sun - could provide an unlimited and cheap source of energy.

But to be viable, fusion power plants would have to produce more energy than they consume, which has proven elusive.

Now, a breakthrough by scientists at the National Ignition Facility (NIF) could boost hopes of scaling up fusion.

NIF, based at Livermore in California, uses 192 beams from the world's most powerful laser to heat and compress a small pellet of hydrogen fuel to the point where nuclear fusion reactions take place.

The BBC understands that during an experiment in late September, the amount of energy released through the fusion reaction exceeded the amount of energy being absorbed by the fuel - the first time this had been achieved at any fusion facility in the world.

This is a step short of the lab's stated goal of "ignition", where nuclear fusion generates as much energy as the lasers supply. This is because known "inefficiencies" in different parts of the system mean not all the energy supplied through the laser is delivered to the fuel.


But the latest achievement has been described as the single most meaningful step for fusion in recent years, and demonstrates NIF is well on its way towards the coveted target of ignition and self-sustaining fusion.

For half a century, researchers have strived for controlled nuclear fusion and been disappointed. It was hoped that NIF would provide the breakthrough fusion research needed.

In 2009, NIF officials announced an aim to demonstrate nuclear fusion producing net energy by 30 September 2012. But unexpected technical problems ensured the deadline came and went; the fusion output was less than had originally been predicted by mathematical models.

Soon after, the $3.5bn facility shifted focus, cutting the amount of time spent on fusion versus nuclear weapons research - which was part of the lab's original mission.

However, the latest experiments agree well with predictions of energy output, which will provide a welcome boost to ignition research at NIF, as well as encouragement to advocates of fusion energy in general.

It is markedly different from current nuclear power, which operates through splitting atoms - fission - rather than squashing them together in fusion.

NIF, based at the Lawrence Livermore National Laboratory, is one of several projects around the world aimed at harnessing fusion. They include the multi-billion-euro ITER facility, currently under construction in Cadarache, France.

However, ITER will take a different approach to the laser-driven fusion at NIF; the Cadarache facility will use magnetic fields to contain the hot fusion fuel - a concept known as magnetic confinement.

192 laser beams are focused through holes in a target container called a hohlraum
Inside the hohlraum is a tiny pellet containing an extremely cold, solid mixture of hydrogen isotopes
Lasers strike the hohlraum's walls, which in turn radiate X-rays
X-rays strip material from the outer shell of the fuel pellet, heating it up to millions of degrees
If the compression of the fuel is high enough and uniform enough, nuclear fusion can result

 

[DiscoJer]

There is something of a running joke, that fusion has been 20 years away for the last 50 years.


Still, we'll figure it out eventually.

 

[BigJonsson]

Power of the sun in the palm of my hand!

 

[Esch]

Power of the sun in the palm of my hand!

 

[Frankenstrat]

Sounds awesome. Hopefully we'll get to see this become viable within a few decades.

Power of the sun in the palm of my hand!

 

[Dead Man]

So they reached the break even point? That is pretty cool if true.

 

[K.Sabot]

More worried about the waste situation myself, but I'm largely uninformed on the intricacies of Nuclear Energy, so my apprehension might be unfounded.

 

[TemplaerDude]

That is the laziest meme pic I've ever seen.

 

[moist]

More worried about the waste situation myself, but I'm largely uninformed on the intricacies of Nuclear Energy, so my apprehension might be unfounded.

The only byproduct of the fusion they are working on at NIF(deuterium–tritium fusion) is helium gas, not radioactive crap to store till we figure out how to deal with it.

 

[The Technomancer]

More worried about the waste situation myself, but I'm largely uninformed on the intricacies of Nuclear Energy, so my apprehension might be unfounded.

This is what I'm curious about as well. What kind of waste, if any, does hydrogen fusion generate?

 

[Dead Man]

More worried about the waste situation myself, but I'm largely uninformed on the intricacies of Nuclear Energy, so my apprehension might be unfounded.

For fusion, yeah it is mostly unfounded.
http://en.wikipedia.org/wiki/Fusion_power#Safety_and_the_environment

The natural product of the fusion reaction is a small amount of helium, which is completely harmless to life. Of more concern is tritium, which, like other isotopes of hydrogen, is difficult to retain completely. During normal operation, some amount of tritium will be continually released. There would be no acute danger, but the cumulative effect on the world's population from a fusion economy could be a matter of concern.[citation needed]

Although tritium is volatile and biologically active, the health risk posed by a release is much lower than that of most radioactive contaminants, due to tritium's short half-life (12.32 years), very low decay energy (~14.95 keV), and the fact that it does not bioaccumulate (instead being cycled out of the body as water, with a biological half-life of 7 to 14 days).[46] Current ITER designs are investigating total containment facilities for any tritium.

The large flux of high-energy neutrons in a reactor will make the structural materials radioactive. The radioactive inventory at shut-down may be comparable to that of a fission reactor, but there are important differences.

The half-life of the radioisotopes produced by fusion tends to be less than those from fission, so that the inventory decreases more rapidly. Unlike fission reactors, whose waste remains radioactive for thousands of years, most of the radioactive material in a fusion reactor would be the reactor core itself, which would be dangerous for about 50 years, and low-level waste another 100. Although this waste will be considerably more radioactive during those 50 years than fission waste, the very short half-life makes the process very attractive, as the waste management is fairly straightforward. By 300 years the material would have the same radioactivity as coal ash.[45]

Additionally, the choice of materials used in a fusion reactor is less constrained than in a fission design, where many materials are required for their specific neutron cross-sections. This allows a fusion reactor to be designed using materials that are selected specifically to be "low activation", materials that do not easily become radioactive. Vanadium, for example, would become much less radioactive than stainless steel. Carbon fiber materials are also low-activation, as well as being strong and light, and are a promising area of study for laser-inertial reactors where a magnetic field is not required.

In general terms, fusion reactors would create far less radioactive material than a fission reactor, the material it would create is less damaging biologically, and the radioactivity "burns off" within a time period that is well within existing engineering capabilities.

 

[K.Sabot]

For fusion, yeah it is mostly unfounded.
http://en.wikipedia.org/wiki/Fusion_power#Safety_and_the_environment

So higher radioactivity with shorter half-life if we're talking about worst case scenario.

Sweat off my brow then! Proceed science, you have bested my worries yet again.

 

[The Technomancer]

So how are they actually going to turn the energy into electricity? Do we have a better method then boiling water to turn turbines yet?

 

[brian577]

So if the ITER is using magnetic containment then what is this project using? I was under the impression that that was the only way to contain a fusion reaction.

 

[Woorloog]

So how are they actually going to turn the energy into electricity? Do we have a better method then boiling water to turn turbines yet?

Can't electric energy be harvested directly from fusion plasma in magnetic containment fusion?
Don't recall the name of the process. I think it wasn't very efficient though.

Steam turbines are rather efficient AFAIK, so not sure why we'd need a better method.

So if the ITER is using magnetic containment then what is this project using? I was under the impression that that was the only way to contain a fusion reaction.

Two primary methods for fusion are magnetic containment and inertial containment. NIF is inertial containment, they squeeze a fuel pellet with lasers until it fuses.

 

[moist]

So if the ITER is using magnetic containment then what is this project using? I was under the impression that that was the only way to contain a fusion reaction.

Lasers running at a stupidly high power, which in turn makes it awesome.

 

[Fusion Pizza]

So if the ITER is using magnetic containment then what is this project using? I was under the impression that that was the only way to contain a fusion reaction.

http://en.wikipedia.org/wiki/Inertial_confinement_fusion

This kind. Really Fucking Cool Stuff.